Apparatus for removing cadmium from zinc ores.



C. P. FISKE,

3 nwwtoz Patented Nov. 13, 1917.

81 149. attain/lugs A P M mu APPARATUS FOR REMOVING CADMJUM FROM ZINC ORES.

APPLICATION FILED Alli-1.24, 19!].

UNITED STATES PATENT OFFICE.

CHARLES POMEROY FISKE, OF PALMERTON, PENNSYLVANIA, ASSIGNOR TO THE NEW JERSEY ZINC COMPANY, OF NEW YORK, N. Y., A CORPORATION OF NEW JERSEY.

APPARATUS FOR REMOVING CADMIUM FROM ZINC ORES.

Application filed August 24, 1917.

To all whom it may concern:

Be it known that 1, CHARLES P. FIsKE, a citizen of the United States, residing at Palmerton, in the county of Carbon, State of Pennsylvania, have invented certain new and useful improvements in Apparatus for Removing Cadmium from Zinc Ores; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in furnaces for effecting the removal of cadmium from zinc ores, and more particularly to improvements in furnaces for carrying out the process or method of removing cadmium from such ores described and claimed in United States Letters Patent No. 1,161,- 885 granted November 30, 1915.

The method of removing cadmium from roasted or naturally oxidized zinc ores described in said Letters Patent No. 1,161,885 involves subjecting the ore to the reducing action of a current of reducing gas, such as producer gas, at a temperature sufficient to reduce and volatilize the cadmium without reducing and volatilizing any substantial quantity of the zinc, for example, at a temperature ranging between 700 C. and 850 C., and carrying off the cadmium thus expelled from the ore. In the practice of this method, as pointed out in the said Letters Patent, it is important to regulate the heating of'the ore and the supply of the reducing gas to obtain the necessary temperature for the desired reaction and to obtain the necessary reducing conditions for this reaction. The furnace of the present invention enables the heating and reducing operation to be efiected in an improved manner, whereby the continuity of the furnace operation can be preserved and the heating action and reducing action independently controlled and regulated.

According to the present invention, a rotating furnace is provided, in which the charge is placed or through which it is passed, this furnace being internally heated and being provided with means for conveying off the expelled cadmium and means for supplying a regulated amount of reducing gas to the furnace, in a preheated state, in addition to the independent heating means Specification of Letters Patent.

Serial No. 187,981. I

for obtaining and controlling the desired temperature within the furnace.

The invention will be further described in connection with the accompanying drawing, illustrative thereof, which shows one embodiment of the improved furnace for effecting the removal of the cadmium from zinc ores.

In the drawing a rotating furnace is indicated at 1, constructed in the usual way of an outer metallic casing with a refractory lining which may be providedwith longi- Patented Nov. 13, 1917.

tudinal ribs (not shown) whose function is to raise the ore and drop it through the atmosphere of the kiln. The kiln is horizontally arranged and supported by suitable bands on supporting rollers 2 and driven in any suitable manner, as by means of the gear 4, from any suitable source of power. The kiln is provided with a charging and discharge opening 3 for the introduction and removal of the ore charged.

Arranged at one end of the kiln, and communicating therewith through the pipe or connection 5, is the fire-box or furnace 6 for heating the rotary kiln. This fire-box is provided with an appropriate grate 7 and ash-pit door 8 and with a regulable charge and draft controlling door 9 operating in guides 10, and counter-balanced by the weight 11 so that it can be readily opened or closed and adjusted to any intermediate degree of opening.

0n the opposite side of the furnace from the outlet 5 is arranged the supply pipe 12 for the reducing gas, preferably producer gas, this supply pipe having an independent regulating valve 13 for controlling and regulating the amount of producer gas thus supplied. The arrangement of this supply pipe 12 is such that the producer gas enters the highly heated upper portion of the furnace chamber and is pre-heated before it passes into the kiln 1 through the connection 5.

At the other end of the rotary kiln, and communicating therewith through the ipe or flue 14, is the settling chamber '15 rom which an exit pipe or stack may lead the escaping gases and unseparated cadmium, to a condenser, (not shown). The settling chamber is provided with suitable vmeans for permitting access thereto for removal of the cadmium separated therein.

In the operation of the furnace for the removal of cadmium from zinc ores, the charge of roasted or naturally oxidized zinc ore is introduced into the kiln through the about the desired intimacy of contact of the and gases.

ore with the heating and reducing flame The heating of the kiln is effected from the fire-box or furnace '6 and this heating action is capable of regulation so that the desired temperature can be maintained throughout the kiln and throughout the treatment of the ore charge. When the charge has been heated to the proper temperature, from 700 C. to 850 0., the reducing gas is introduced through the pipe 12 and its amount is regulated by the regulating valve 13. This reducing gas mingles with the products of combustion of the firebox 6 and is itself highly pre-heated so that it enters the kiln 1 along with the gases from the fire-box and at the same temperature. If the productsof combustion from the fire-box are oxidizing, the excess of producergas will partly burn and supply added heat, it being thus possible to supplement the heat of the fire-box by the heat of combustion of part of the producer gas,

while it is still possible to supply an excess ofthe producer gas for securing the desired reducing atmosphere within the kiln.

This independent regulation of the firebox and of the reducing gas supply makes it possible to increase or decrease the heating efi'ect, by proper regulation of the fire-" tion can be carried out in a continuous manner with appropriate regulation of the temperature of the charge in the kiln and independent regulation of the reducing atmosphere within the kiln.

It will be understood that variations and modifications can be made in the specific construction of the apparatus illustrated and described without departing from the spirit and scope of the invention.

I claim 1. An apparatus for removing cadmium from zinc ore comprising a rotary kiln for agitating the ore charge and bringing it into intimate contact with the atmosphere of the kiln, means for bringing a current of heating gases directly into contact with the agitated ore charge and for regulating said current and the temperature of the ore charge, an independent regulable supply means for supplying a regulable current of reducing gas to the kiln for obtaining a reducing atmosphere, and means for recovering the cadmium expelled from the ore; substantially as described.

2. An apparatus for removing cadmium from zinc ore comprising a rotary kiln for agitating the ore charge and bringing it into intimate contact with the atmosphere of the kiln, a fire-box provided with means for regulating the combustion therein arranged to heat the interior of the kiln by means of the products of combustion from such fire box, means-for supplying a reducing gas to the upper portion of said fire-box so that the reducing gas mingles with the products of combustion and passes therewith in a pro-heated condition to the kiln, and independent means for regulating the supply of such reducing gas, substantially as described.

In testimony whereofIaflix my signature.

CHARLES POMEROY FISKE'. 

